Process of dehydrating emulsions



PROCESS OF DEHYDRATING EMULSIONS. v APPLICATION r1150 MAYIZ, 1919. RENEWED MAY 31,1921.

1 ,405,125. 7 Patented Jan. 31, 1922.

2 SHEETSSHEET 1- c U C E llllllllllllllllllH \HHHIHHHH NJEMMQ 5M Wf/w/ F. W. HARRIS.

PROCESS OF DEHYDRATING EMUILSIONS. v APPLICATIQN FILED MAYI2,19.1'9. RENEWED MAY 31,1921. 1,405,125.,

Patented Jan. 31, 1922.

2 SHEETS-SHEET 2- UNITED STATES PATENT OFFICE.

FORD W. HARRIS, OF LOS ANGELES, CALIFORNIA, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO PETROLEUM RECTIFYING COMPANY, OF SAN FRANCISCO, CALI- FORNI A, A CORPORATION OF CALIFORNIA.

PROCESS OF DEHYDRATING EMULSIONS.

Specification of Letters Patent.

Patented Jan. 31, 1922.

Application filed May 12, 1919, Serial No. 296,641. Renewed May 31, 1921. Serial No. 473,771.

sions, of which the following is a specification.

invention relates to the art of dehydratmg petroleum emulsions. Petroleum oils as found in nature often contain water which may be arbitrarily classified as free water or trapped water. It is common practice in the art to allow the oil to stand in sumps or in tanksfor the purpose of al-' lowing the water to-settle out, and a great deal of the water found in, the oil may be so separated. It is common practice in the art to designate the water which willbe settled out by gravity within" a few days as free water.

In addition to the free water there is often a considerable quantity of water in the oil which will not settle out within a reasonable time, this water being ordinarily found in the form of small or even microscopic particles or globules. This emulsifiedwa- 'ter may be conveniently designated as trapped water. There is of course no sharp line of demarcation between trappe water and free water, the water often being found in all sizes of globules from the microscopically minute to particles which are easily visible to the naked eye. m

It is the object of my invention to provide a process by which practically all water, whether trapped or free, may be readily I viewed from above.

removed from petroleum oils.

Further objects and advantages will be made evident hereinafter.

Referring to the drawings which are for illustrative purposes only,

Fig. 1 is a sectional levation of my invention. I

Fig. 2 is a plan on line 22 of Fig. 1 as line 3-3 of Fig.1 as

Fig. 3 is a plan on viewed from above.

' In the form of apparatus used to carry on my invention illustrated in the drawing I provide a. tank 11 having a tight bottom 12 and a tight top 13. Secured in a flange 14 near the bottom thereof, is an inlet ipe 15 which extends across the tank an is or conical contour. -A steam coil 19 may be placed inside the tank directly above the inlet plpe 15 and a water gauge 20 may be placed on the side 'ofthe tank for indicating differences in oil level between planes wa and 12-6.

Secured considerably above the plane aa, which represents the maximum water level, is a plurality of grounded electrodes,

25, the electrode shown being flat plates Secured on pipe members 26 carried'in suitablebrackets 27 fixed t0 the tank. All the plates- 25 are mechanically and "electrically connected together and form what may be termed the grounded electrode. A plurality of plates 30 are supported on pipe members 31 which are carried on insulators 32 which are in turn carried on suitable members 33 fixed to the tank. The plates 30 are mechanically and electrically connected together and form what may be termed the live electrode. The plates 30 extend downwardly parallel to and equally spaced from the plates 25, forming with the plates 25 d an electric field in which thedehydration is carried on. 1

An insulator 40 .is secured in the top of the tank, this insulator being preferably formed of porcelain and being pressure tight, a conductor passing therethrough and being connected through a wire 42 with the plates 30. A transformer 50 is provided,

the high tension secondary 51 thereof being.

connected at one side to the tank 11 at 52, and at the other side to' the conductor 41. The primary 53 of this transformer is connected to one of the stationary contacts 54 of a safety switch 55. This safety switch is provided with a bridging contact 56 which connects the two stationary contacts 54 together. The other contact 54 is con- 63, the bridging contact 56 being pulled into contact with the members 54: when the float assumes its extreme top position. This float is so placed that it rises to the highest part of the tank and tends to open the circuit between the contacts 54 at all times that the tank is not entirely filled with liquid by moving the bridge member 56.

A water outlet is provided, this water outlet rising inside a drain column 71 which is connected to a drain 72 and being provided at its upper end with a long threaded sleeve 7 3 which can be moved up and down on the pipe 70 so as to change the upper level of the sleeve 73 as shown at c-0. A valve is placed in the pipe 18, by means of which pressure may be maintained on the tank 11.

The method of operation of my invention is as follows: 7

Oil under pressure is delivered through the valve 17 to the interior of the pipe and passes through the perforations 16 therein, rising through a body of water which has been placed in the bottom of the tank, the level of this water being easily observed by means of the gauge glass 20 and the height thereof being regulated by the members 70 to 73 somewhere between the levels aa and bb, as will hereinafter be explained. This both. free and trapped water. The body of water into which the oil is injected is preferably heated by means of the steam coil 19 to facilitate the separation of the free water from the oil, this separation taking place as the oil rises through the body of water, the purposes of the perforations 16 being to finely divide the oil into a plurality of small streams from which the free water particles readily separate, attaching themselves to the body of water and forming a portion thereof. If for any reason water alone is supplied through the valve 17 it simply becomes a part body of water in the bottom of the tank, the height of this water being automatically regulated as will hereinafter be explained.

The plates 25 and 30 are secured inside the tank at some distance above the highest level a-a which the water is allowed to reach. They are therefore at all times maintained in a body of oil which contains little or no free water, the free water being caught and removed, as has just been explained, by the body of water in the bottom of the tank. An electric potential is maintained between these plates due to the secondary 51 of the transformer 50. This potential causes electric currents to flow through the emulsion between the plates and may conveniently have a magnitude somewhere between 5,000 and 20,000 volts.

For the purpose of preventing sparks in the tank when it is partially filled with entering oil may contain of the theory is, in short,

oil, thus having a body of gas and air in the top, the safety switch 55 is provided, this safety switch only closing the circuit to the primary 53 of the transformer 50 when the tank is entirely filled, and opening it whenever the level of the oil in the tank falls so that an air space is formed in the top of the tank. In practice the safety switch 55 is never called upon to operate except at times when the treater is being started or when some accident occurs.

WVhen the treater is in operation it is maintained full of oil and under some pressure by a suitable regulation of the valve 17. For the purpose of regulating the flow of water the members 70 to 73 are provided, the members 70 to 7 3 forming a continuous pipe, the upper level 0-0 of which can be readily regulated. As this pipe is in communication with the water in the bottom of the tank it is at all times filled with water and the column of water so formed is balanced against the combined water and oil inside the tank and the pressure produced by the valve 80. As a result of the difference in gravity between the oil and water there is a tendency for water to overflow or to rise above the level 0-0 whenever the water in the tank rises above the level 0ta the level of water falling below the level 0-0, whenever the water in the tank falls below the level bb. Inv the event that water is supplied through the pipe 15 it is automatically drawn off through the pipe 70 as soon as sufficient accumulates to raise the level in the bottom of the tank tothe continues to flow through the pipe 70 until the level falls to the line 6-7). During the operation of the treater there is a continual precipitation of water and a. more or less continuous drawing off of the water. The waterwhich overflows from the top of the pipe 73 falls downwardly inside the column 71 into a drain 72.

It will be seen radically fromv the well known fact that by current through a body of emulsion one 18' able to change trapped water into free water. In the patents to Frederick G. Cottrell, Nos. 987,114, 987,115, 987,116, 987,117

that my invention differs previous art. It is apassing an electr c line aa and the water and 994,377, a general theory of the action of electrical dehydrators is set forth. This that, upon the impressing of an electric motive force between electrodes immersed in oil, there will result a number of water chains, the supposition being that the small water particles line themselves up in more or less continuous lines.

It is considered by Cottrell and others that the passage of current across these chains" tends to break the oil film between inevitably the water globules and to cause them to coalesce into larger masses. I am not sure whether this action actually takes place or not. I am, however, sure that it is highly desirable to form a large number of the chains, and I am further sure that these chains when formed have a strong attraction for each other, which, to my mind, fully accounts for the coalescing action which I believe to be merely the union of a large number of chains of trapped particles into one chain in which all or part of the individual particles may be large enough to be designated as free water.

I have further found the principal problem in the dehydration of oil is to prevent the introduction of masses .of free water into the field between the electrodes. It will be noted that in my dehydrator a body of water is maintained in the bottom and all entering liquid must pass through this water. It will be further noted that by sopassing the entering liquid I am able to catch and separate free water particles and thus prevent them from getting into the space between the electrodes.

I have further found that there is a contlnuous and rapid circulation around the plates 25 and 30 of my dehydrator, the oil rising rapidly through the space between the outslde plates and the walls of the tank 11. Th1s is due in part to the cooling action of the outer walls of the tank 11 which causes a slow settling of the oil near these walls, this 011 being replaced by hot oil which rises between the plates 25 and 30. The circulation is further. promoted by the formation of gas bubbles between the plates 25 and 30 which in rising greatly assist in circulating the liquid.

I have further found that any water particles which are of sufiicient size to be designated as free water seem tobe caught at the lowest point of travel of the circulating oil, or perhaps continue to fall until they reach the body of water in the bottom of the tank. In any case I have found. that it is unnecessary to provide any means for preventing the formation of water chains as set forth in the Cottrell patents and I have further found that after a short period of operation that the body of oil above the water is largely dehydrated so that at its worst it contains only a few per cent of water.

I have further found that there is a stratification of the oil, the dry and clean oil ris-' tice with a dehydrator of this type to remove all the water but a small fraction of one per cent from a very stubborn emulsion.

In the operation of all previous commercial types of dehydrators it has been common practice to dehydrate the oil in open tanks. As there is some liability of sparks passing across the top of the liquid in such tanks and as the mixture of oil, gas and air in the top of such tanks is highly inflammable, a considerable number of fires have resulted and there have been large property losses and some loss of life due to the operation of these open type dehydrators. I have found that it is entirely practical and indeed desirable to operate in closed tanks which are entirely filled with oil. It will be noted that in my dehydrator the outlet pipe is taken out of the extreme top and the safety switch 55 is provided so that there is no potential on any parts inside the dehydrator except when it is practically filled with oil. It is therefore impossible for explosions or fires to occur.

I have further found that is is highly desirable to keep the valve 80 partially closed for the purpose of maintaining a pressure upon the interior of the dehydrator. This I believe is due to the fact that there is a tendency for gas bubbles to form in the space.

between the plates 25 and 30 and by maintaining a pressure on the oil the formation of these bubbles is somewhat retarded.

I claim as my invention:

1. Aprocess for dehydrating an emulsion which consists of first passing said emulsion into a body of water through. which the emulsion rises due to its different specific gravity and to which, it ives up its larger particles of water and t ereafter the said emulsion is caused to pass through an electric field whereby the particles of water are caused to agglomcrate and settle by grav1ty, after which the water and the oil are separately withdrawn.

2.. A process of dehydrating an emulsion as set forth in claim 1 wherein the said treatment takes place under a pressure above that of the atmosphere.

3. A process of dehydrating crude 011 as set forth in claim 2 wherein heat is applied to the body of emulsion to facilitate the separation of the water and the oil.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 7 day of May, 1919.

FORD W. HARRIS. 

